Pad drilling is the process of drilling several wells in an area, with the goal being to efficiently extract hydrocarbons (or other fluids in a subterranean reservoir) from the several wells in parallel. “Walking” rigs are sometimes employed for pad drilling. Walking rigs include devices and structures that give the rigs the ability to move from one well center to another, separated by a relatively short distance, and drill the wells in sequence, while minimizing the non-drilling time required to move the rig.
Typically, the ground is too soft, is not sufficiently level, or otherwise is not conducive, in its natural state, to such walking operations. Accordingly, a pad is generally prepared to give the rig a solid, level foundation. This is done by excavating several (e.g., 10) feet of dirt, and then filling the resulting hole with clay, shale, or some other suitable substrate material. This substrate material is then packed down, and a layer of soil cement may be poured over it, thereby providing a suitably firm and level pad site for the rig.
This process is labor and time intensive. Further, the resulting semi-permanent pad, which is useful for walking the rig while drilling the multiple wells, may remain and impact the environment after drilling operations are complete, or may need to be removed, which can be expensive.